With electrophotographic copying machines, the surface of the photoconductive member is uniformly charged by a charger and then exposed to the image of an original to form a latent electrostatic image, which is thereafter converted to a visible image with toner particles. After the toner image has been transferred to copy paper, the toner and charges remaining on the surface of the photoconductive member are removed therefrom to make the photoconductive member repeatedly usable. Thus, after the transfer of the toner image during such a copying cycle, the residual charges are removed from the photoconductive surface to reduce the surface potential approximately to zero volts, permitting the charger to give a uniform potential to the photoconductive surface for the subsequent copying cycle. When the charge eraser malfunctions for one cause or another, completely or substantially failing to operate properly, the copy image is adversely affected, while the potential will abnormally build up on the surface of the photoconductive member, possibly causing damage thereto.
Although such faults are inherent in the operation of the eraser, conventional copying machines are not specifically adapted to detect the malfunction of the eraser and to effect the desired control in the event of malfunctioning.
Moreover since the malfunction of the eraser is usually very difficult to detect for the user, it is substantially impossible to preclude accidents such as damage or breakdown of the photoconductive member. In that context, there is also a need to provide a system for detecting the malfunction of the eraser and automatically controlling the charger and the like.